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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 9 (Instrument Panel System Displays And Gauges) >> Diagnostic Information and Procedures >> DTC B0158 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF disconnect the harness connector at the ambient air temperature sensor.
  2. Ignition OFF, test for less than 1 ohm of resistance between the ambient air temperature sensor low reference circuit terminal B and ground.
    • If greater than 1 ohm, test the low reference circuit for an open/high resistance.
  3. Ignition ON, verify the HVAC module displays approximately -40°F (-40°C).
    • If the HVAC module does not display approximately -40°F (-40°C), test the ambient air temperature sensor signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC module.
  4. Ignition ON, perform an ambient air temperature sensor Instant Update to by pass filtering by simultaneously pressing the following switches on the HVAC control module:
    • LEFT TEMPERATURE UP
    • PASS ENABLE
    • REAR DEFOG ENABLE
  5. Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the ground circuit of the OAT sensor. Verify the DIC displays approximately 87.5°C (189.5°F).
    • If the HVAC does not display approximately 189.5°F (87.5°C), test the ambient air temperature sensor signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC module.
  6. If all circuits test normal, test or replace the ambient air temperature sensor.
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